Thermostat problem? the car doesn't warm up all the way. Anyone?

[GWerks]

So, I have noticed that if I do city driving in a 65-80º day the car warms up and the needle stays where it's supposed to, but if I go on the highway, or 55mph road for a while it never warms up all the way.

Here is where it usually sits on highway:


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But last night it was coldish out and seriously, the needle was standing right before the third mark. In the morning, the car takes forever to warm up. I imagine this is affecting my gas mileage somewhat. I just got the car also, so yeah.

Should I flush the coolant? Thermostat stuck open?

Thank you guys.

[Rated S]

Either your thermostat is stuck open or your coolant temp sensor is broken. The CTS is MUCH easier to replace (its behind the intake manifold), and it's a relatively cheap part. Takes 4 minutes to replace. I'd start with that.

[KNaudi]

is it fluctuating or just staying colder than normal? fluctuations usually means bad CTS.

[GWerks]

I have only owned the car for 1 week now. And if I let it iddle after driving it the needle actually goes where it's supposed to, and does not over heat or anything. But if I go on the highway and it's cold out the car cools off too much (picture).

[mholme]

That sounds like a thermostat issue if it's dropping with speed increase. As mentioned, I would still replace the CTS first and hope for the best.

[GWerks]

Alright, yeah, sounds like the thermostat is stuck open, anyone know where it's at? complicated to get to it?

[Rated S]

Alright, yeah, sounds like the thermostat is stuck open, anyone know where it's at? complicated to get to it?

Behind the timing belt.

Enjoy your B5 S4.

[audiluxary]

^^ Like said before start with you CTS because it is cheap and easy to fix. Thermostat would require a lot more work/money and you might as well do your whole timing belt and water pump while your in their.

[jgr5027]

this actually is happening to my car at the moment. can someone link me to getting a CTS?

[Rated S]

http://www.purems.com/products/product.php/II=1472

It would be smart to order the clip. I always seem to break mine off removing the one sensor.

[mholme]

http://wiki.audiworld.com/index.php/...or_Replacement

[audiluxary]

http://www.purems.com/products/product.php/II=1472

http://www.mjmautohaus.com/catalog/p...oducts_id=1207

http://www.ecstuning.com/Audi-B5_S4-...ooling/ES1484/

Take your choice, get the little black plastic clip as well in case you drop or break the original one it's only $.55.

[audiluxary]

What the fuck too late, I think MJM is the cheapest.

[GWerks]

Let me tell you guys something, the car while it's a iddle warms up all the way, it's when I get on the highway that it cools down. I imagine, it's not the Coolant Temperature Sensor, because if it was it wouldn't work at all. Like I said, it's only when the car is getting more air in the radiator or it's cold out that it doesn't warm up all the way. I highly doubt that this CTS would be causing this, but I would give it a try.

[GWerks]

Behind the timing belt.

Enjoy your B5 S4.

haha damn it!

[KNaudi]

http://www.purems.com/products/product.php/II=1472

It would be smart to order the clip. I always seem to break mine off removing the one sensor.

2nd this. I broke mine the same way.

[Rated S]

haha damn it!

Yeah I lived with a stuck thermostat for about 15 months because I wasn't due for a timing belt for another 20k when it started.

[GWerks]

Yeah I lived with a stuck thermostat for about 15 months because I wasn't due for a timing belt for another 20k when it started.

Well, my timing belt isn't due for an other 25k miles so yeah... were these your symptoms?

[DRA4]

My doesn't go all the way to the middle too, but i think is a bad cluster. I already did timing belt, water pump and CTS. Also my gas gauge doesn't go all the way to full.

[Rated S]

Well, my timing belt isn't due for an other 25k miles so yeah... were these your symptoms?

Yeah. It would run cold, but not all the time; it was sparatic. If i used the heater it would drop cold immediately.

[GWerks]

I ordered a new cluster last week with the same miles my car has! So we'll see. If not I will do the CTS and hopefully that will fix it.

[99ebpsi24]

Does your heat blow hot air or does it put out cool air? I'm having an issue with my heat at the moment and I'm thinking my t-stat is going out because I'm getting zero heat but my car warms up all the way.

[Dimcorner]

I had a CTS fail and a Thermostat fail.

With the Temp sensor the needle would randomly go from dead cold to working temp in a matter of 10 seconds. And I mean randomly. On highway, standing at a light, in traffic, etc. Replaced and all was good.

I found out my thermostat was busted when I drove up to Boston during christmas. Right around South Carolina my needle was not all the way up. Around NJ it was barely above cold. I taped the lower intake openings for the radiator with gorilla tape and it went up to normal temp (it was 40 outside). It would also take FOREVER to warm up. Replaced and all was good.

Thermostat is behind the timing belt. I was trying to get to it without taking the TB off, but no dice. Had to mark off both cams and belt and just slowly take off the TB of the passenger cam. To get to that the following had to come off...

Front bumper
unhook top coolant line for radiator
unhook all electrical connectors by the PS reservoir
unbolt PS cooling line from front of radiator
Slide front carrier (with radiator) to service position
take off bi-pipe on passenger side
take off belt cover
untension accessory belt and slide a lock pin into it
untension timing belt (after marking the cam) and slide lock pin into it
slide off belts
unbolt the cover for the thermostat
clean and replace (use gasket goop is recommended).
reverse procedure, fill up with coolant.

Total time: about 4 hours

[Dimcorner]

Does your heat blow hot air or does it put out cool air? I'm having an issue with my heat at the moment and I'm thinking my t-stat is going out because I'm getting zero heat but my car warms up all the way.

I noticed that I had my outside temp sensor loose and when it was screwing with my AC temp. It thought it was way cold/hot outside so when i put 70 inside it would blow hot air (or reverse if it thought it was super hot outside and I just wanted 70).

[edoushe]

Behind the timing belt.

Enjoy your B5 S4.

HAH! seriously, change the green coolant temp sensor ($20 from mjmautohaus) very easy change, fixed my car, i was having low boost/sporadic boost problems, if thats not it, check the brown coolant temp sensor in you radiator.

[edoushe]

http://www.purems.com/products/product.php/II=1472

http://www.mjmautohaus.com/catalog/p...oducts_id=1207

http://www.ecstuning.com/Audi-B5_S4-...ooling/ES1484/

Take your choice, get the little black plastic clip as well in case you drop or break the original one it's only $.55.

i second this right here.